Commands tagged bash String Manipulations (5)

  • This type of join is clearly documented in the bash manual. Only the first character of IFS is used for the delimiter. Show Sample Output


    3
    (IFS=,; echo "${array[*]}")
    aspiers · 2013-09-25 10:36:38 0
  • When you have different digital cameras, different people, friends and you want to merge all those pictures together, then you get files with same names or files with 3 and 4 digit numbers etc. The result is a mess if you copy it together into one directory. But if you can add an offset to the picture number and set the number of leading zeros in the file name's number then you can manage. OFFS != 0 and LZ the same as the files currently have is not supported. Or left as an exercise, hoho ;) I love NF="${NF/#+(0)/}",it looks like a magic bash spell.


    2
    OFFS=30;LZ=6;FF=$(printf %%0%dd $LZ);for F in *.jpg;do NF="${F%.jpg}";NF="${NF/#+(0)/}";NF=$[NF+OFFS];NF="$(printf $FF $NF)".jpg;if [ "$F" != "$NF" ];then mv -iv "$F" "$NF";fi;done
    masterofdisaster · 2010-11-08 22:48:56 2
  • I like to label my grub boot options with the correct kernel version/build. After building and installing a new kernel with "make install" I had to edit my grub.conf by hand. To avoid this, I've decided to write this little command line to: 1. read the version/build part of the filename to which the kernel symlinks point 2. replace the first label lines of grub.conf grub.conf label lines must be in this format: Latest [{name}-{version/build}] Old [{name}-{version/build}] only the {version/build} part is substituted. For instance: title Latest [GNU/Linux-2.6.31-gentoo-r10.201003] would turn to title Latest [GNU/Linux-2.6.32-gentoo-r7.201004]"


    1
    LATEST=`readlink /boot/vmlinuz`; OLD=`readlink /boot/vmlinuz.old`; cat /boot/grub/grub.conf | sed -i -e 's/\(Latest \[[^-]*\).*\]/\1-'"${LATEST#*-}"]'/1' -e 's/\(Old \[[^-]*\).*\]/\1-'"${OLD#*-}"]'/1' /boot/grub/grub.conf
    algol · 2010-04-21 19:16:51 0
  • You define your variable MYVAR with the desired search pattern: MYVAR= ...which can then be searched with the find command. This is useful if you in a script, where you want the arguments to be fed into the find command. The provided search is case insensitive (-iname) and will find all files and directories with the pattern MYVAR (not exact matches). This may go without saying, but if you want exact matches remove the \* and if you want case sensitive, use the -name argument.


    0
    find . -iname \*${MYVAR}\* -print
    Buzzcp · 2010-08-04 05:43:51 0
  • Demos figlet/toilet fonts in a configurable dir. Show Sample Output


    0
    for i in ${TOILET_FONT_PATH:=/usr/share/figlet}/*.{t,f}lf; do j=${i##*/}; toilet -d "${i%/*}" -f "$j" "${j%.*}"; done
    trevorj · 2011-12-27 00:49:42 0

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Re-read partition table on specified device without rebooting system (here /dev/sda).

count the number of specific characters in a file or text stream
In this example, the command will recursively find files (-type f) under /some/path, where the path ends in .mp3, case insensitive (-iregex). It will then output a single line of output (-print0), with results terminated by a the null character (octal 000). Suitable for piping to xargs -0. This type of output avoids issues with garbage in paths, like unclosed quotes. The tr command then strips away everything but the null chars, finally piping to wc -c, to get a character count. I have found this very useful, to verify one is getting the right number of before you actually process the results through xargs or similar. Yes, one can issue the find without the -print0 and use wc -l, however if you want to be 1000% sure your find command is giving you the expected number of results, this is a simple way to check. The approach can be made in to a function and then included in .bashrc or similar. e.g. $ count_chars() { tr -d -c "$1" | wc -c; } In this form it provides a versatile character counter of text streams :)

Add prefix onto filenames
Best to try first with -n flag, to preview

To create files with specific permission:

Benchmark report generator
Nicely display in html format a detailed report of the machine, including cpu benchmarks.

recursive search and replace old with new string, inside files
Using -Z with grep and -0 with xargs handles file names with spaces and special characters.

Interactively build regular expressions
txt2regex can be interactive or noninteractive and generates regular expressions for a variety of dialects based on user input. In interactive mode, the regex string builds as you select menu options. The sample output here is from noninteractive mode, try running it standalone and see for yourself. It's written in bash and is available as the 'txt2regex' package at least under debian/ubuntu.

Stop long commands wrapping around and over-writing itself in the Bash shell
add the command either in /etc/profile or ~/.bash_profile so that this is available to your shell.

Bitcoin Brainwallet Base58 Encoder
A bitcoin "brainwallet" is a secret passphrase you carry in your brain. The Bitcoin Brainwallet Private Key Base58 Encoder is the third of three functions needed to calculate a bitcoin PRIVATE key from your "brainwallet" passphrase. This base58 encoder uses the obase parameter of the amazing bc utility to convert from ASCII-hex to base58. Tech note: bc inserts line continuation backslashes, but the "read s" command automatically strips them out. I hope that one day base58 will, like base64, be added to the amazing openssl utility.

Show demo of toilet fonts
Lists a sample of all installed toilet fonts


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